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- icrc2007@icrc2007.unam.mx
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Latitudinal distribution of galactic cosmic ray density and its effect on the CIR-driven modulations of density and density gradient measured by the Muon detector network
Speakers
- Mr. Yoshitaka OKAZAKI
Primary authors
- Mr. Yoshitaka OKAZAKI (Department of Geophysics, Tohoku University, Japan)
Co-authors
- Dr. Kazuoki MUNAKATA (Faculty of Science, Shinshu University, Japan)
- Dr. Paul EVENSON (Bartol Research Institute, University of Delaware, USA)
- Dr. Marcus L. DULDIG (Australian Government Antarctic Division, Australia)
- Dr. John E. HUMBLE (School of Mathematics and Physics, University of Tasmania, Australia)
- Dr. Nelson J. SHUCH (Southern Regional Space Research Center, Brazil)
- Dr. Marlos R. SILVA (National Institute for Space Research, Brazil)
- Dr. Alisson D. LAGO (National Institute for Space Research, Brazil)
- Dr. Ismail SABBAH (Faculty of Science, Kuwait University, Kuwait)
- Dr. Hiroshi FUKUNISHI (Department of Geophysics, Tohoku University, Japan)
- Mr. Akira FUKUSHITA (Faculty of Science, Shinshu University, Japan)
- Mr. Takuya NARUMI (Faculty of Science, Shinshu University, Japan)
- Mr. Tatsuo CHIBA (School of General Education, Shinshu University, Japan)
- Dr. Shin-ichi YASUE (School of General Education, Shinshu University, Japan)
- Dr. Chihiro KATO (School of General Education, Shinshu University, Japan)
- Dr. Takao KUWABARA (Bartol Research Institute, University of Delaware, USA)
- Dr. John W. BIEBER (Bartol Research Institute, University of Delaware, USA)
Files
Abstract content
Richardson et al. [1996] statistically investigated CIR-driven modulations of Galactic Cosmic Ray (GCR) density with the data obtained by satellites. By examining depressions caused by CIRs with and without the Sector Boundary (SBs), they concluded that SBs do not organize the GCR density. On the other hand, a 22-year cycle in the amplitude of depressions was also confirmed. They suggested that this is caused by changes in large-scale heliospheric magnetic field. In order to reveal an effect of the large-scale magnetic field on GCR density distributions, we have investigated a relationship between interplanetary magnetic field and GCR density gradient measured by the Muon detector network. It has been found that GCR density tends to have its maximum (minimum) at SBs when A is positive (negative). We have also investigated individual CIR-driven modulation, distinguishing whether or not CIR includes a SB. Moreover, assuming a slab-shaped modulated region we have deduced the structure reproducing the observed variations of GCR density and density gradient. For 2001-2006 (A is negative), the structure which has its maximum of GCR density along a SB tends to be deduced in case of CIR with a SB. We will report these results.
Reference
Proceedings of the 30th International Cosmic Ray Conference; Rogelio Caballero, Juan Carlos D'Olivo, Gustavo Medina-Tanco, Lukas Nellen, Federico A. Sánchez, José F. Valdés-Galicia (eds.); Universidad Nacional Autónoma de México, Mexico City, Mexico, 2008; Vol. 1 (SH), pages 367-370
